Social vigilance is one candidate behavior potentially linking a stress as well as a broad array of individual, social, and contextual stress moderators to cardiovascular disease. Social vigilance reflects a sensory intake process akin to Lazarus and Folkman's conceptualization of stress appraisal where an environment or potential threat is continually monitored and reappraised in order to detect any change in status. Although social vigilance may be an adaptive behavior, sustained vigilance or hyper vigilance may have important health consequences. Data from our respective labs demonstrate that social vigilance evokes exaggerated cardiovascular responses acutely and potentiates larger cardiovascular responses to a subsequent stressor, a mediating pathway linking psychological stress to increased physical disease risk. However, there are no published studies examining the association between vigilance and objective markers of cardiovascular disease. Therefore, the current proposal aims to examine social vigilance as moderator of atherosclerotic risk in a representative community sample as well as test hypotheses regarding acute physiological reactions to vigilance in daily life as a mediator of the stress-related change in atherosclerosis. Social vigilance will be assessed with 2 methods. First, a psychometrically validated measure developed by our lab will be used to assess self-reported behavior. Second, ecological momentary assessment (EMA) will be used to assess the frequency of vigilant behavior at 45-min intervals over a 2-day period in participants' daily lives. The EMA protocol will be paired with ambulatory blood pressure assessment such that each vigilance sampling will be paired with a blood pressure measurement. Ambulatory blood pressure is a demonstrated mediator of atherosclerotic progression. Atherosclerosis will be assessed with 2D ultrasound imaging of the carotid arteries. The carotid ultrasound scan and EMA/ambulatory protocol will be performed at study entry and at a 2 year follow-up. We expect that greater social vigilance (higher self-report, more frequent daily experience) will be associated with higher carotid IMT scores at each time point and predict IMT progression over time. We also expect that daily blood pressure reactivity to vigilance will mediate the effects of vigilance on carotid IMT progression. The results of this study will contribute to an understanding of the basic behavioral pathways linking social stress to CHD risk and inform targeted interventions to modify such behavior.